Improvement in processes for bleaching paper pulp



FIPSU? mproyement in,Process for Bleaching Paper PuIQ,-;Q ParentedAprnmyiaz.

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laaste UNITED STATES PATENT OFFICE.

JOHN CAMPBELL, OE OHAT'EAM lvILLAeENEw YORK.

IMPROVEMENT lN PROCESSES FOR BLEACHING PAPER PULP.

Specification forming part of Letters Patent No.125,658, dated April 16, 1872.

' Specification describing certain Improve- In, the said drawingArepresents Van ordinary beatingen gine,

l tion of pulp, with rotating beaters,

v"back fall a. provided with hinged covers, b,'and a pipe for such as used for the prepa- B, and rIhe vat of the engine is to be carrying off the gases from the engine, and

leading them into a chamber, to be utilized in the bleaching of yarns, fabrics, &c. 'llrcre'is a rotary or other suitable blower, C, for foreing a current of air through a pipe, D, into the engine and near the bottom thereof. I prefer d 'to locate this pipe soas to discharge the eurrent of air inthe direction in which the pulp is caused to travel in the vat of the engine; and .there may be4 two such blowers, one-at each end. The chemicals to be hereinafter described are put into a vessel, G', which com municates, by a vertical pipe, E','with the blastpipe D, from theblower. The pipe E is provided with a stopper, F, or other equivalent stopper, valve, or cock. The delivery end of the pipe E extends into the pipe D, and for a short distance within it and oi' less diameter, and concentric with the pipe D, so that the blast of air may pass around the inner pipe E. The delivery end of this pipe E should be above the level 'of the pulp in .the engine.

The pulp or other fibrous matter to be bleached .is put into the engine with a weak solution of chlorine liquor of one-eighth of a degree Baume, or Jupward, depending upon the material to be bleached, as some fibrous substances require a greater strength than half a degree. This charge I prefer to work in the engin from ten to twenty minutes before ap- Y plying the blast of air with other chemicals. The other/,chemical agents are charged into the vessel G, as follows: For the bleaching of six hundred pounds of pulp made from wood, I take about three pounds of oxalic acid dissolved in about six gallons of hot water.

"llo this solution I add four pounds of porous alumina, freed from iron, previously dissolved in three gallons of hot water; and I then add half an ounce of bromine previously combined with half a gallon of chlorine liquor, such as put into the engine with the pulp.

After the above compound has been charged into the vessel Gr the blower is` started, and

then the stopper F is opened to permit the liquor to flow intoj the blast-pipe D, where it is acted upon by the current of air, which vaporizes it, and the air so charged is forced into 4 the engine, and the blast continued forabout half an-hour. The blast is then stopped, the cover of the engine removed, and thel engine continued inoperation until the. bleaching is completed.

The aperture in the bottom of the vessel G, leading intov the pipe, should be small, so that the charge will take about fteen minutes to pass through. y

I have above described what Ideem the bestyngredients and proportions thereof, and mode ot' treatment for bleaching six hundred pounds of pulp made from wood; but I do not wish to be understood as limiting my claim of invention to speeiiie ingredients and proportions, as other equivalent acids may be substituted, and for some kinds of fibrous substances, such as cotton-waste, flax-waste, or colored rags, sulphuric acid would be preferable to oxalic, and so with hydrochloric acid, and so as to the other ingredients.

When applying my said process to the bleaching of yarns and woven, knitted, or felted fabrics, the engine must be adapted thereto by removing the back fall a', and beaters B, and

. substituting any suitable agitator.

The gases which escape from the vat of the en gine through the4 escape-pipe are, by thesaid pipe, delivered into any suitable chamber, and there utilized for bleaching yarns, or described, for bleaching brous substances by abrcs suspended therein. the use ot' bromine in connection with the othhave discovered that by the use of broer chemical agents specified mine, vegetable colors are readily discharged having like properties. from brous substances. JOHN CAMPBELL.

at I claim as my invention, and desire to l'Witllessess secure by Letters Patent, is A. J. DE LACY,

The process, substantially as herein-above -WM. SCOTT. 

